I'm currently in the process of doing the transfer as I type this. I have a fully modded wii with HBC, Wiiflow, DIOS MIOS, and a few forwarder channels. In preparation for the transfer I did a NAND backup this morning, and then used MODMii to download IOS62 and the new Wii Shop Channel. I began on the WiiU (you have to). You need to boot up Wii mode and then run the already included wii transfer utility. I say included, but what it is is a stub that points you to the Wii Shop channel to download the tool. I think its the exact same download as the one for the wii, it just knows its on a WiiU so it gives you those menus. It asks you for an SD card, verifies it, downloads something to it (I didn't think to check what, oops). You then take that SD card out and put it in your Wii console. Once you've got the SD card, you turn your Wii on and start up the Wii transfer on it. It verifies the SD card (with the transfer tool on it) and connects to the internet. It is at this time that both consoles need to be connected to the internet. It verifies a transfer is possible and then begins copying the contents of your NAND to the SD card. Once its done, you put that same SD card back into the WiiU and it begins copying stuff back over. I'm about 70% finished at this point (takes longer on the WiiU portion than on the Wii portion). While this is going on, I went back to check on the state of the Wii. Bootmii was still in boot2. Priiloader was still working, and it attempted to boot up Wiiflow instead of the system menu. I had issues from this point. Wiiflow found no partitions or config files. I quit to homebrew channel and it didn't show anything. After futsing around with it, I decided to boot into bootmii and restore my NAND. This went on without a hitch, and I rebooted. Same trouble as before. It was at this point I realized there was something awry with the SD card (or more specifically, the SD card adapter I was using with my micro SD card). I switched out to a different adapter, cold booted everything, and VIOLA, the wii operated exactly as I had left it when I backed up this morning. Bam. I'll update this with the state of Wii mode on the WiiU once the transfer is finished. Just wanted to give a heads up to folks who might be worried about losing their Wii softmods. EDIT: Transfer is finished, and as expected no HBC got moved to the WiiU. Wiiconnect24 does not work, so letterbomb is not possible either. But it seems there's no danger in doing the transfer tool with a modded Wii.